Magnetic time element



L. W. THOMPSON. MAGNETIC TIME ELEMENT.

APPLICATION FILED m. 16. 121's.

1 ,3 1 6,984. I Patented Sept. 23, 1919.

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i m; E5 h )0 v: H Inventor: -i s.\ S v4 a Louis W. Thompson,

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His JTttorheg UNITED STATES PATENT OFFICE.

LOUIS W. THOMPSON,

or scnmmcmnr, new Yomlc, ASSIGNOR 'ro GENERAL nmc'rmc comm, Aoonrom'non' or NEW YORK.

MAGNETIC TIME ELEMIHVT.

To all whom it may concern:

Be it known that I, LOUIS W. THOMPSON, a citizen of the United States,residing at Schenectady, in the county of Schenectady, State of NewYork, have invented certain new and useful Improvements in Magnetic TimeElements, of which the following is a specification.

My invention relates to devices of the character in which a time elementis interposed between the initiation of-an action and its completion andmore specifically it relates to electro-magnetic switches in which aninterval of time elapses between the act which initials and the finalact which completes. Various means have been devised for efiecting sucha time element, one of the commonest being the. dash-pot.Electromagnetic switches provided with a dash-pot for delaying theaction of a switch member are very commonly employed but because ofinherent defects in the dash-pot they have not uniforml been regardedwith favor. One of the ob ects of my invention is to provide a timeelement device which is free from the difliculties experienced in theuse of dash-pots and similar devices, and which is mechanically simpleand uniformly effective.

In carrying out my invention I employ, as controlling elements, a magnetwhich is preferably a permanent magnet and an armature arranged so thatit will normally be in contact with the magnet. One of these members (inthe form which I have shown as the magnet) is arranged to vibratethrough its normal position and as it vibrates freely the amplitude willgradually decrease. During the vibration attractive forces will not besufficiently great to cause the movement into contact but as theamplitude decreases the attractive force increases as it approaches thenormal position until finally the movement takes place. I have foundthat if the vibratory member is mounted to move freely and it is alwaysgiven the same initial deflection that the time limit will always be aperfectly definite one.

The device which I have shown is an electromagnetic switch in which thedeflection of the pivoted magnet is controlled by an electromagnet, thedeflection being maintained until the condition of the electromagnet isreversed. The armature, which is Specification of Letters Patent.Patented Sept. 23, 1919. Application filed February 16, 1918. Serial No.217,849.-

' attracted by the permanent magnet, is arranged to operate a switch sothat there will be a definite time interval between the reversal of thecondition of the electromagnet and the operation of the switch.

In the accompanying drawing illustrating 'one form of my invention,Figure 1 is an elevation of a complete device; Fig. 2 is an end view ofthe same, and Fig. 3' shows one system of electrically connecting myimproved switch.

Referring to Figs. 1 and 2, 10 represents a permanent magnet which Ihave shown as of the horseshoe type mounted in a bracket 11. Thisbracket 11 is secured to shaft 12 which is mounted in bearings 13. Thesebearings are preferably of the antifriction type, as, for instance, ballbearings, so. as to permit the magnet to vibrate with a minimum amountof friction. Cooperating with the permanent magnet is an armature arm 14which is pivoted at 15 in a bracket 15 so as to rest against a stopscrew 16 when it is not attracted by the magnet. As shown, the armaturecomprises an arm which may be of non-magnetic material and amagneticportion 17 of magnetic material which "is attracted by the magnet. Asshown", this magnetic portion is cylindrical in form and secured to thearm b a clamp 17 so as to project on both si es of the arm opposite thepole pieces of the magnet. Thin non-magnetic sleeves 16' around themagnetic ortion 17 prevent the latter from freezing to the magnet. Theswitch, which is operated by the armature, comprises a bell crank member18 pivoted. at 19, provided with a contact member 20 cooperating with astationary contact 21. The contacts 20 and 21 are held in engagement bya spring arm 22 which engages the end of the bell crank lever. Anelectromagnet 23 acts on the spring arm and by pulling it downwardforces the arm 14 downward slightly so as to assist in releasing the arm14 from the magnet 10.

The vibratory 0r reciprocatory movement of the magnet 10 is initiated byelectromagnet 24 having an armature 25 pivoted at 2'6. Attached to thearmature 25 is a finger 27 which engages a projection 28 on the bracket11 which supports the magnet. The pivot of the magnet 10 is verticallyabove the armature portion 17 so that normally. the magnet will hangvertically as shown in Fig. 1 with its pole pieces directly over themagnetic portion 17 of the armature. Wlth the magnet in this position,the armature 14 will be drawn up by the magnet as shown in Fig, 1. If,however, the electromagnet 24 is energized the magnet 10 will bedeflected to the right as shown in Fi 3, and the armature will bereleased and rop into engagement with the stopscrew 16 as shown in Fig.3. Since the armature of the electromagnet 24 acts ,on the magnet 10 wth a leverage which is short as compared with the leverage at which themagnet 10 is held by its armature, I utilize the magnet 23 for assistinthe magnet 24. The magnet 23, b 2% orces the arm 14 away from the magnetthereby reducing the effort requlred of the magnet 24. I may, therefore,make the magnet 24 smaller than would otherwise be the case. Assumingthat the parts are 1n the pos1- tion shown in Fig. 3, if the magnet isreleased it will vibrate on its pivot, swinging back and forth throughits normal posltion. Each time the pole pieces of the magnet pass themagnetic portion 17 there is a tendency for the armature to be liftedbut the force is not applied sufliciently long to lift it. As the armcontinues to vlbrate,

' however, the amplitude of the movement gradually decreases until apoint is reached where the force is sufiicient to attract the armaturearm. .At this point the armature arm will be lifted into contact withthe magnet which will thereupon stop vibrating and the switch 18controlled by the armature will be operated.)

In Fig. 3 I have shown my devlce ut1l1zed as a time-limit overload relayfor controlling the low voltage coil 29 of the c1rouit breaker 30. Thewinding of the electromagnet 24 is connected in series with thewinding23 and the circuit of these two magnets is controlled by an overloadrelay 31. Under normal conditions, the electromagnet 24 being energized,will hold the pivoted member 27 in a deflected posltion as shown in Fig.3 and the switch contacts 20 and 21 will be held in firm contact by thespring member 22 assisted by electromagnet 23. On the occurrenceof anoverload, however, electromagnets 23 and 24 will both be deenergized.The effect of the deenergization of the magnet 24 is to release thepivoted magnet and allow it to swing freely on its pivot but thedeenergization of the ma net 23 has no-practical eflect. If the over oadshould only continue for a short time, the overload relay will dropandrestore the original conditions, but if the overload persists beyond thetime which is predetermined, the magnet 10 which is swinging and all thetlme approaching a stop, will reach a point where the armature 14 puling downward on the spring armbreaker. When norma conditions arerestored to the line, the electromagnet 23 be- I ing energized, forcesthe arm 14 slightly away from the magnet 10 and at the same t1me theenergization of electromagnet 24 deflects the magnet 10 so as to be inreadi- 4 ness for the next overload. I find that the operation of thedevice is improved b reducmg the width of the pole faces 0 the magnet 10and of the armature as much a possible in the direction of vibration,

thereby reducin the length of the interval during which t 0 full forceof the magnet is efl'ective in the armature. As shown, I do this byrounding the pole ends of the magnet and using a cylindrical member foran armature. It will be seen that I have provided a very simple devicefor giving a very definite,timeinterval and while I have described theprinciple of operation of my mvention, together with the ap aratus whichI now consider to represent t e best embodiment thereof, I desire tohave it understood that the apparatus shown is only illustrative,andthat the invention can be carried out by any other means.

What I claim as new and desire to. secure by Letters Patent of theUnited States, is

1. A time element device comprising a magnet and an armature normallyattracted into contact with each other and means for causing one of saidparts to reciprocate with reference to the other through the normalposition at a gradually decreasing amplitude until the magnetic.attraction causes movement into contact.

2. A time element device comprising a magnet, a movable armaturenormally attracted thereby, means for causing .one of said parts toreciprocate through the normal position at a gradually decreasingamplitude until the magnetic attraction causes the armature to move intocontact with the magnet.

3. A time element device comprising a pivoted magnet, an armaturenormally attracted thereby, means for causing the magnet to reciprocatethrough its normal tion at a gradually decreasing amplitude until themagnetic attraction causes the ar--- mature to be attracted into contactwith the osipivoted magnet, an armature normally attracted thereby andelectromagnetic means for initialing a reciprocatory'movement of themagnet on its pivot through its initial position at a graduallydecreasing amplitude until the magnetic attraction causes the armatureto be attracted into contact with the magnet.

6. A time element switch comprising a magnet and an armature normallyattracted into contact with each other, means for causing one of saidparts to reciprocate with reference to the other through the normalposition at a gradually decreasing amplitude until the magneticattraction causes movement into contact, and a switch actuated by saidmovement.

7 A time element switch comprising a magnet and an armature normallyattracted into contact with each other, means for causing one of saidparts to reciprocate through the normal osition at a graduallydecreasing amplitu e until the magnetic attraction causes movement ofthe other part, and a switch actuated by said movement.

8. A time element switch comprising a pivoted magnet, an armaturenormally attracted thereby, means for causin the magnet to reciprocateon its pivot t rough its normal position at a gradually decreasingamplitude until the magnetic attraction causes the armature to beattracted into contact with the magnet, and a switch operated by thearmature.

9 A time element switch comprising'a pivoted magnet, an armaturenormally at: tracted thereby, electromagnetic means for initialing areciprocatory movement of the magnet on its pivot through its normalposition at a gradually decreasingamplitude until the magneticattraction causes the armature to-be attracted into contact with themagnet, and a switch operated by the armature.

10. A time element switch comprising a magnet and an armature, one ofwhich is pivoted, normally attracted into contact with each other, anelectromagnet for deflecting the pivoted part from normal andsubsequently releasing it so that it will reciprocate through-its normalposition at a gradually decreasing amplitude until the magneticattraction causes the armature to be attracted into contact with themagnet, and a switch operated by the armature.

11. A time element switch comprising a permanent magnet pivoted tovibrate freely, a movable armature normally attracted by said magnet,and an electromagnet arranged to deflect the permanent magnet from itsnormal position and release it when the condition of the magnet isreversed so that the permanent magnet will vibrate through its normalposition at a gradually decreasing amplitude until the magneticattraction causes the armature to be attracted into contact with themagnet.

12. A time element switch'comprising a pivoted magnet an armaturenormally attracted thereby, an electromagnet arranged to deflect thepermanent magnet from its normal position and release it when thecondition of the magnet is reversed so that the permanentmagnetwillvibrate through its normal position at a gradually decreasingamplitude until the magnetic attraction causes the armature to beattracted into contact with the magnet, a switch operated by thearmature and an electromagnet energized simultaneously with thedeflecting electromagnet for controlling the armature.

In witness whereof, I have hereunto set my hand this 15th day ofFebruary, 1918. LOUIS THOMPSON.

